Create a sandbox on a Clover cluster, and put some simple graph in it (eg/ with a 60 second sleep or something similar)
Set max_running_concurrently = 1, enqueue_executions = true on the sandbox
Using the clover SOAP Web Service interface, attempt to run more jobs than there are cluster nodes, so that queueing must occur. For my testing I used Soap UI to generate the requests.
In the Clover Web GUI -> Executions history, see all the jobs are created, and either running or pending
Notice that in Soap UI, the web service calls do not receive a response until the job actually starts executing in Clover